Hello, if you have any need, please feel free to consult us, this is my wechat: wx91due

School of Computer Science: assessment brief

The Feistel cipher is a symmetric block cipher encryption framework which is the basis of many modern day encryption algorithms. In this coursework you will implement a Feistel cipher system as a software implementation in Hack Assembly.

In a Feistel cipher the plaintext, P, to be encrypted is split into two equal size parts L0 and R0 such that P = L0R0. A function F is applied to one half of the plaintext, combined with a key, and the result is XOR’d with the other half of the plaintext.

Feistel ciphers often employ multiple rounds of this scheme. In general the scheme works as follows, for all i = 0, . . . , n,

To decrypt an encrypted message using this cipher we can apply the same procedure in reverse. For i = n, n − 1, . . . , 0,

For this coursework we are interested in the 16-bit Feistel cipher which uses 4 rounds.

2. Assessment tasks

(a) Write a program (XOR.asm) in HACK assembly that implements a bit-wise XOR function between two 16-bit values stored in RAM[3] and RAM[4] and stores the result in RAM[5]. [4 marks]

(c) Write a program (FeistelEncryption.asm) in HACK assembly, that implements the described Feistel encryption system. The initial key, K0, will be stored in RAM[1], and the plaintext to be encrypted will be represented by a 16-bit value stored in RAM[2]. The result of the encryption should be stored in RAM[0]. [10 marks] 

[Total 22 marks]

3. General guidance and study support

Tools required to simulate the hardware and CPU are provided on Minerva under Learning resources: Software. You may find it easier to implement cipher in a high level language first. This will also allow you to test the results of your HACK program.

Support will be available during lab classes. Please ensure the files you upload work with the test files provided and use the filenames provided in this sheet.

This coursework will be automatically marked using Gradescope. Feedback will be provided through Gradescope.

These will not necessarily be the same tests that are provided to help you develop the solution. You should therefore test your solution thoroughly using other values for the plaintext and keys before your final submission.

5. Presentation and referencing

Submitted code should provide suitable comments where possible.

Links to submit your work can be found on Minerva under Assessment and feed back/Submit my work. The HACK assembly (asm) files for each part must be up loaded individually. Ensure you use only the filenames provided in this specification sheet.

Academic integrity means engaging in good academic practice. This involves essential academic skills, such as keeping track of where you find ideas and information and referencing these accurately in your work.

By submitting this assignment you are confirming that the work is a true expression of your own work and ideas and that you have given credit to others where their work has contributed to yours.

8. Use of Gen AI (Generative Artificial Intelligence) instructions

There is a three-tier traffic light categorisation for using Gen AI in assessments.

• This assessment is red category. AI tools cannot be used.

9. Assessment/marking criteria

• Part a) is graded using 4 tests, each worth 1 mark. [max 4 marks]

• Part b) is graded using 4 tests, each worth 2 marks. [max 8 marks]

• Part c) is graded using 4 tests, each worth 2 marks and a further 2 marks for optimised solutions that require a lower number of operations to complete the encryption [max 10 marks]